Do It Yourself | Liquid Urethane Motor Mount Inserts

A complete guide to modifying stock motor mounts to make your own motor mount inserts

Do It Yourself Liquid Urethane Motor Mount Replacement Before
Do It Yourself Liquid Urethane Motor Mount Replacement Final

If you’ve already done your research, you know for sure you want the DIY motor mount, skip down to the actual creation of the motor mount insert. But if you need a little convincing, keep reading.

A breakdown of the article:

But first…

Before you dive into creating your own motor mount insert, its a good idea to understand the few basic principles of motor mount inserts and why you would even want to use them. There’s pros and cons, like everything, in making your motor mounts more solid. So before you do, here’s a few pros/cons:

The Pros

  • Increase Horsepower Potential
  • Reduce Wheel Hop
  • More Responsive Motor

The Cons

  • Increase Cabin Vibration
  • Increase Cabin Noise

So taking those pros and cons a bit deeper, the first and foremost reason to firm up your motor mounts is to hold the engine firmly in place. Often the more pliable stock motor mounts allow the engine to move excessively – resulting in wheel hop and loss of power. The more extreme version of this is when an owner has to increase the vehicle’s horsepower more than the stock motor mounts were designed to handle. This can cause tearing of the stock motor mounts as well as damage to the engine and engine bay should the engine be allowed too much movement.

Easily the most frustrating result of solid motor mounts is increased vibration felt by passengers in the vehicle. Stock motor mounts are designed with a fair amount of flex, designed to absorb natural motor vibration and reduce vibration noise. In most cases, this increase in noise and vibration is not terribly significant, however, it is increased by the firmness of the urethane used to fill the mount and the number of mounts that are filled.

Do It Yourself Liquid Urethane Motor Mount Replacement Cabin Noise

Cabin Noise, Really?

The trade off for increased performance is cabin noise and vibration. The harder, more firm your motor mounts are the more efficiently they will transfer horsepower to the wheels. Likewise, the softer the motor mounts are the less vibration and noise will be transferred to the rest of the vehicle. There are a number of ways to make the trade off between vibration/noise increase and performance.

Firming up the Correct Motor Mounts

Most Front Wheel Drive vehicles have several motor mounts, typically 4 or 5. Some of the motor mounts are designed significantly different from the others. TORQUE mounts are the motor mounts designed to reduce the amount of engine movement when power is applied. Main Mounts are the mounts designed to support and hold the weight of the engine.

Torque mounts are the most effective mounts at providing a great rigidity to the engine assembly without transmitting as much natural vibration to the driver. Torque mounts are typically located at the front end or rear of the engine. Main mounts are typically located higher on the engine assembly as the engine weight usually hangs from these.

While it is typically possible to firm up all the mounts on a vehicle – the torque mounts will provide the best trade off between performance and vibration.

Using a Softer or Harder Universal Motor Mount Insert Formula

There are several firmness or “durometer” levels offered:

  • 60A – For the Daily Driver – This is the softest formula offered that will still make a noticeable difference in vehicle performance. This softer formula is best for tuners that still want to increase performance without trading off as much personal comfort.
  • 80A – Even trade off between performance and vibration – When it comes to motor mount inserts, this formula is the most popular for its ability to significantly increase vehicle performance while still allowing some small amount of flex in the mounts to keep vibration and noise to reasonable levels.
  • 80A HIGH PERFORMANCE – The next best step – A newer version of the most popular choice balances high performance with ride quality, while boasting a higher tear rate and standing up to heat even better.
  • 94A – Race Quality – Not for the daily driver. This formula is the hardest of the 4 available. Providing the best reduction in motor movement – this version will also allow a rather significant amount of engine vibration to be transmitted into the vehicle. Best you can get without going with an aluminum mount.

Do it Yourself Liquid Urethane Motor Mount Replacement Choices

With four choices in hardness, there is a formula for any level of performance

Materials Required for this Project:

All items listed are absolutely required in order to complete this project safely and easily. In total they shouldn’t cost you more than $10 from your local Home-Depot or Wal-Mart (aside from the actual urethane). Save yourself future frustration and buy these before starting the project!

  • Liquid Urethane – available in the 60A, 80A, 80A High Performance, and 94A
  • Contact Cement – Helps the duct tape seal against greasy surfaces
  • Duct Tape – Seals one side of the mount
  • De-greaser – Cleans the mount of grease and oil
  • SAND – in a box – vital to the project – DO NOT skip this step
  • Level – makes sure the mount if level for a level pour

Do It Yourself Liquid Urethane Motor Mount Replacement Materials

Instructions –
DIY Motor Mount Inserts

Prepping The Mounts

Step One – CLEAN!

For the urethane to bond correctly and to ease the overall process – the mounts must be thoroughly cleaned of grease and dirt. A little cheap degreaser can go a long way over simple soap. Take the time to use real degreaser – it’s usually just a spray on – spray off process anyway.

Do It Yourself Liquid Urethane Motor Mount Replacement Clean

Cleaning the mounts with a degreaser will allow the urethane to properly bond to the rubber

Step Two – Sealing One Side

The motor mount inserts are made by pouring a liquid urethane into the voids of the mounts and allowing it to dry. In order to do this you’ll need to completely seal off one side of the mounts. When you first pour the urethane into the mounts it will have a very liquid consistency. Even the smallest hole in your sealing jobs will allow the urethane to seep out.

Do It Yourself Liquid Urethane Motor Mount Replacement Cement

Contact cement will give you an improved seal job to ensure your urethane stays in the mount

The best way to do this is with some contact cement and duct tape. While duct tape alone will usually work – the contact cement will ensure a good seal – especially if there’s any greasy residue on the mounts (the tape will not adhere properly). Start by painting the outside edge and inside circumference of the side of the mount you’re going to seal off – with contact cement. Anywhere you need to be sure there’s a good seal – use this liberally – you’ll be able to pull/scrape it off later.

Do It Yourself Liquid Urethane Motor Mount Replacement Contact Cement

Once you’ve set a good layer of contact cement, seal off the mount with the duct tape. Use several strips of tape at different angles from the center of the mount. Continue adding tape around the center of the mount until you’ve sealed it off completely. Some users wont have the center piece sticking out of one side and won’t have to work around it – either way just keep adding tape until it’s properly sealed off.

Do It Yourself Liquid Urethane Motor Mount Replacement Tape Start

Duct tape is cheap – so use as much as necessary until you feel good about the job – then add a little more.

Do It Yourself Liquid Urethane Motor Mount Replacement Tape

The better the tape job, the better the mount will turn out

Setting Up the Mounts

It’s important that the mounts are completely level before you pour the urethane into them. If they’re laying at an angle the mount will not turn out right.

Prepare a small box of sand for the mounts. Setting the mounts into the sand will serve two purpose:

  1. Allow a perfectly level placement – even if there are protrusions from the mounts that would otherwise make it sit screwy
  2. Help seal off any small holes in your sealing job. If the hole is small, a little urethane will leak out into the sand and the sand will help it congeal faster – effectively sealing the hole in the mount

Do It Yourself Liquid Urethane Motor Mount Replacement Sand

DO NOT attempt to do this without the sand box. While it is possible to do so – using the sand box will help ensure you do the job right the first time. Once you mix the urethane, you’ll only have 15-20 minutes of working time before the urethane is to firm to pour. You won’t have enough time to decide you SHOULD have used the sand box.

Do It Yourself Liquid Urethane Motor Mount Replacement Level

Don’t skip the sand and the level, once you mix the urethane you won’t have time to realize you shouldn’t have skipped this step

Mixing the Urethane

DO NOT DO THIS UNTIL YOU’RE 100% Ready to Pour!

The correct mixing ratio is absolutely VITAL to the urethane setting correctly. That’s why each set comes in a pre-measured container. Do not attempt to use only PART of a kit – doing so may cause the urethane to not set correctly

Each kit should include:

  • Urethane – in the hardness level you ordered. Comes in small paint can style container
  • Activator – a very liquid substance in a small bottle
  • Stirring Stick

Do It Yourself Liquid Urethane Motor Mount Replacement Contents

Before doing ANYTHING with these substances read through all the warnings and adhere to them! Most importantly – mix and use these outside in a well ventilated area.

Do It Yourself Liquid Urethane Motor Mount Replacement Open
Remove the lid from the larger paint can containing the urethane and set it aside. Take the bottle of activator and shake it well before adding it to the urethane.

Do It Yourself Liquid Urethane Motor Mount Replacement Mix

Thoroughly mix the activator and urethane with the provided mixing stick.

Do It Yourself Liquid Urethane Motor Mount Replacement Stir
Be sure to scrape the sides of the can and even scrape off the stirring stick to ensure you’ve mixed all of the urethane in with the activator.

Once you’ve mixed the urethane and activator you’re ready to pour it into the mount! Once the urethane is mixed you only have about 15-20 minutes where it’s pour-able!

Pouring the Urethane

Slowly pour the mixed urethane into the open side of the mounts. Allow for the urethane to fill all the voids in the mount. It may take a minute for it to settle completely flat – so take your time. If it seems to be leaking out a LITTLE – don’t panic – the sand will help clot up the hole and slow the leak.

Fill the mounts to the top – it’s even OK if some spills over the outside edge.

Once the mounts are full wait about 10 minutes. In 10 minutes the urethane should still be very liquid and you can top off the mounts with the remaining urethane in the can. This is particularly important if you have a small leak in the sealed side of the mount. Don’t wait longer than 20 minutes to check up on the mounts as by that time the urethane will start to become less workable.

Do It Yourself Liquid Urethane Motor Mount Replacement Pour
Do It Yourself Liquid Urethane Motor Mount Replacement Last Pour

A Job Not So Well Done

It is very important that you use sand. If you do a poor job of setting up the mount in your sand, your results can be disastrous. If there is any type of hole in your seal job, the urethane can seep out. The sand can stop that, so be sure to pack the sand under the mount in order to clog any leak. If not, you get this:

Do It Yourself Liquid Urethane Motor Mount Replacement Bad Sand

If the urethane seeps out like this, you’re final product will be less than desired. Check out the mount we did with a poor sand job:

Do It Yourself Liquid Urethane Motor Mount Replacement Bad

Make sure you pack in the sand and keep the mount level, otherwise you’ll get this..

The Finished Product

By the next day you should be able to take the mounts out of the sand box and remove the tape from the opposite side. Sometimes if you had a small leak you’ll find small clumps of sand attached to the other side – these pry/peel off easily and will not affect your new mounts.

Do It Yourself Liquid Urethane Motor Mount Replacement After1

The tape should pull off easily and if you want to clean them up further you can scrape off the left over contact cement – however if you really don’t care too much you could even leave the tape on – it won’t hurt anything.

Do It Yourself Liquid Urethane Motor Mount Replacement After2
Do It Yourself Liquid Urethane Motor Mount Replacement After3

Finished “Do It Yourself” Motor Mounts

Do It Yourself Liquid Urethane Motor Mount Replacement final1

Additional Notes For Users

Some users have asked if this will work for their mounts if the center portion has completely torn away from the rest of the mount. The answer: YES! The only additional consideration is the correct centering/alignment of the mounting point that goes through the mount. While the sandbox will make it significantly easier to do this – special care will be needed to ensure centering and alignment.


In using these instructions and urethane kits you accept complete responsibility for the outcome of your project. Only you can ensure this is done correctly and we will not be held responsible if your mounts do not turn out like you wanted.

A significant amount of information has been provided here – however some projects may be unique and will need special attention or a different mode of creation. While we’re happy to help with any questions – we cannot guarantee the outcome of your particular project.

You may not copy, post or reproduce this “How To” information or pictures without written consent from Diverse Suspension Technologies.

Do-It-Yourself Mount Mount Inserts

30 thoughts on “Do It Yourself | Liquid Urethane Motor Mount Inserts

    1. Hey Alex,

      We looked around and couldn’t find a satisfactory answer to your question, but we here at DST do not know the word “defeat”, so what did we do? We cracked open a can of urethane, mixed it up, and poured it into a measuring cup.

      When everything settled, it came out to 400mL which is roughly 13.52fl oz or 1 2/3 cups. We hope this helps!

    1. Thanks Jimmy,

      The process isn’t too hard and it’s awesome to be able to tell your buddies, “I made my own motor mounts”.

      Has anyone had success with pouring their own urethane motor mounts? Please post pictures or tell us how it turned out!

    1. We love Moog too Jimmy!

      Moog is the official suspension of NASCAR and every cup champion for the last 50 years has used Moog ball joints and in those 50 years they have never had one fail.

      Moog has a great history and they are always innovating, like with the new integral dust boot on some of their ball joints that holds it’s seal longer than the traditional design and has less of a chance of being torn because of its low profile.

      Moog is just a great brand that we’re happy to provide to people who need reliable replacements.

      Happy trails.

  1. hey i will like to have psi ratio for eatch grade sound to be 1800 psi for the 95a is it right?
    so its should be higher then 3m High Viscosity urethane work at 1000psi ?
    and the dry time 24h per support? need to make hole to prevent air buble?

    1. Hey Friend,

      The tensile strength of the 94A is around 3120 psi and that of the 60A is 1250 psi. Most of the urethane products I found from 3M were purposed for windshield adhesive so the tensile strength was considerably lower than this urethane, which is meant for more heavy duty purposes such as motor mounts. The curing time is listed at 24-48 hours at a temperature of 77 degrees.

      As we are skirting the edge of my understanding of chemistry I will link these fact sheets for the 94A urethane and 60A urethane products that we carry. These should be able to answer any other technical questions you might have, but if not let us know and we will get you an answer, if one can be found.

      To answer your question about the air bubble prevention we would need a little more information about the application for which you might be using the liquid urethane kit. You can give us a call at 1-888-406-2330 to discuss it in more detail.

      Thanks for the questions!

    1. Hello Zeeshan!

      That’s a great question! The feedback we have been given from other customers is that a kit can cover from 2 to 4 mounts. Unfortunately, it’s really impossible for us to say. Different factors could affect the outcome, such as the size of the mounts or the amount of wear and tear on the mounts. I can tell you each kit, with components completely mixed and settled, yields 400 ml or 1 2/3 cups.

      If you have any other questions or concerns, you can live chat or call our amazing customer service team.

  2. Hello. This looks like a very interesting product, but I’m wondering if it could be used for other applications. I am looking to cast custom radiator mounts (isolation pads) and I’m thinking the 60A might just work. I am using an aluminum radiator on a steel framework, so my main concern is vibration and fretting, wearing through the aluminum radiator. If you have any other suggestions for a better option, please feel free to share.

    Clint Comer

    1. Hey Clint,

      We love that people are using this kit to innovate and come up with some new DIY projects! Polyurethane can definitely function as a radiator isolation pad, but the specific durometer is going to be a preference choice.

      The “softest” formula we offer is the 60A which, while setting up firmly, will still allow some give. The 94A is the most rigid of the formulas and the 80A and 80A High Performance sit in between the two. In any case, polyurethane provides a stiff connection while absorbing vibration, so there are definate possibilities for making your own radiator mounts. I can reference some fact sheets that we have on the 94A urethane and 60A urethane to give you a better idea of the properties of these products and help you decide which might be best for your purposes.

      Has anyone else tried using one of these kits for a DIY radiator mount, or some other application? We would love to hear about it!

  3. What is the mixing ratio between the urethane and activator if you don’t want to waste it all for one mount? I heard 10:1 by weight, so 100 grams of urethane to 10 grams of activator? Is this correct?

    1. Hey Aaron,

      We love experiments! But in this case we have to stick with the instructions.

      The manufacture is pretty serious about these urethane kits being premeasured to exact amounts. Once you start trying to separate a specific portion (including the unmixed chemicals) and save some for later you are playing with some delicate ratios and the quality of the end product can’t be guaranteed. We’re not saying that it can’t be done, but we are saying “don’t do it” in the “we’re not responsible for what happens if the instructions aren’t followed exactly” sense.

      Because of this we would suggest using the entire can and pouring inserts for all of your motor mounts since you need to mix all of the components to achieve the proper chemical compound and the mixed product will set up after about 20 minutes. We love it when people find different ways to use this product but we can’t say for certain that it will set right if the mixing directions are not followed exactly. We urge caution if you decide to not follow the directions and wish you luck.

      That said, has anyone else tried using only part of the activator and urethane? Did it set correctly?

    1. Hey John,

      This is a tricky question since it will depend on the formation and other factors that could affect the formation of the final product. I’m still waiting on some confirmation from another source, but what I have so far says the 80A High Performance kit can operate between -40°F and 195°F. I will double check those numbers and get back to you hopefully by the end of the week (because of the holiday).

      Has anyone used a polyurethane mount near the exhaust manifold with good or bad results?

      Thanks for the question John, and I’ll get back to you when I have another source to confirm those numbers.

  4. I want to make new mounts for a car where noise and vibration isolation is of paramount importance. I has a set of old worn ones which I removed.

    The rubber in the old mounts is crushed solid so I would remove it all so that I’m left with only the clean metal parts. I would use 60A urethane.

    My question is: should I make removable inserts to create the pockets of the original mount or should I make it solid? It seems that a solid mount leaves no room for much movement of the central spigot whereas with rubber-free pockets, the central spigot has freedom to move slightly in all directions and damp out more of the energy of the vibration.

    1. Hey Martin,

      That’s a tricky question. First off since most rubber sits around 50A durometer the 60A polyurethane is a pretty comparable fit.

      Second, voids will typically reduce the NVH that makes it’s way from the engine but in some cases voids can actually increase NVH. SuperPro is a poly bushing manufacturer that has experimented with voids in poly bushings and after a good deal of trial and error came up with a specific configuration of voids that produced the desired result for some of their motor and differential bushings.

      superpro voided polyurethane bushing

      All this to say, it’s not really possible to know that making your own voids will decrease the NVH in your vehicle and it could be a long process to find the right shape, size, etc. void for your mount.

      Good luck Martin and if you do some experimenting let us know how it turns out.

  5. Do I need 1 kit per mount? Or should I do a dry run with sand to see about how much one of my mounts I’ll take.???
    I want to make sure I have enough for my 3 mounts on my Dodge Neon.

    1. Hey David,

      Using sand to get a rough estimate is an interesting idea, unfortunately I can’t vouch for how accurate it might be. The urethane does settle after it’s been poured and should be topped off after about 20 minutes so that might throw off your numbers a bit.

      If I knew the year model of your Neon I could make a more informed guess, but I can’t really say for certain how much urethane you’ll need. To be safe I would say one kit per mount but that will almost certainly be overkill. The mount used in the article is from a Honda Del Sol so it is probably comparable to your Neon and it took about 3/4 of a can. Just remember, once you mix the activator you can’t save any of the urethane for later, it’s “use it” or “use it as a paper weight”.

      Good luck with those motor mounts David.

  6. I’m building a 1955 Chevy truck on a S10 frame. The stock leave springs have a front cushion that is no longer available. Can I use this product to cast pads, and if so, which formula should I use. I’d use one of your body bushings for this purpose, but I need a width of at least 3”.

    1. Hey Alan,

      I spoke with our ASE certified mechanic and he said you should be fine using a mold and pouring your own pads. He suggested using the 80A High Performance which will last you much longer than a rubber alternative and still offer a little give so the ride isn’t too rough.

      If you have any other concerns or questions please feel free to contact our customer service staff and we would love to know how the pads turn out.

      Good luck with the build, Alan.

  7. The amount for the Neon would probably be one kit .
    I poured the torsion mounts upper and lower big end only for my Pt cruiser and only used half the product .

    AT the time I bought the product there were only two durometer available ( that I know of ) I bought the softer and it turns out that for my driving the product is too hard giving engine vibration and noise that is a bit excessive . That could possibly be mitigated by not filling the void completely level full as when that is done there is much more material in the available space than the factory mounts use . Even so my finished product is much less harsh than a tubular racing design torque mount I had been using .
    I had to do something because any of the factory mounts used in my turbo PT would break very easily ( not racing ) .

    1. Thanks for sharing your experience!

      We do offer 4 different durometers from 60A to 94A covering the daily driver and the track car, and yeah, polyurethane is going to give you a better performance-to-smoothness ratio than metal alternatives.

      In theory not filling the void completely should be fine, but your results might vary in terms of increased throttle response and longevity. Another alternative I have heard of is sticking foam or another soft material in the mount as you pour in the poly, making your own voids as it were. Can anybody vouch for this working?

      Thanks again.

    1. Hey Gerrity,

      The minimum curing time for this DIY Urethane product is 7 days. You can accelerate the process considerably by sticking the project in the oven at 150° and the mounts should be good to go in approximately 18 hours. Caution: Make sure you don’t move the mounts around too much while the urethane is still setting up. Once you’ve topped off the mount give it a day before moving it to allow it to firm up and maintain it’s shape.

      Feel free to shoot us any more questions and good luck if you decide to pour your own inserts!

  8. I have a 1966 Pontiac Star Chief Executive that my dad bought new and I am in the process of restoring. The automatoc transmission has a support that runs attaches to both frame sides and the support actually is inserted in the rubber mount that is then bolted to the frame. The rubber is about 1 inch thick and about 1/2 inch surrounds the flat cross support. This part is not available anywhere and I think the poured polyurethane can be an effective solution. However, I have no clue as to stiffness. It feels at least as soft as the owls radiator support pads. Suggestions or thoughts? Is the 80a a good bet or softer/harder. No clue. I have already purchased a few of your suspension products for this rebuild.

    1. Hey Fred,

      That sounds like a fun project you’ve got there! As far as the durometer for your DIY job, it really depends on what you’re looking to do with your Pontiac. If you want to use this as your daily driver or just restore your car a 60A durometer would give you more longevity and only be a touch harder than rubber. If you’re looking for a little bit of a performance upgrade in your throttle response then an 80A is your ticket. Now, if you want to soup-up your Star Chief or race it then you might consider going up to an 80A H.P or 94A to keep everything in place when you really take off.

      Do it Yourself Liquid Urethane Motor Mount Replacement Choices

  9. B. Vanderhoof said he used half of the kit, could you tell us how you measured the mixed percentage? thanks
    I understand seller suggested full mix, used to have experience of mix ratio for epoxy, some has 1:xx ratio hard to do, some has 1:1 ratio easier to be done.

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